Detachable drill bit



May 16, 1939.

C. A. HIRSCHBERG DETACHABLEDRILL BIT Filed Feb. 19, 1956 3 Sheets-Sheet l ag. lg 59 1A.?

IN VEN T OR VATTORNEY CHeRLEs fihwscname.

May 16, 1939. c. A. HIRSCHBERG DETACHABLE DR ILL B IT Filed Feb. 19, 1936 3 Sheets-Sheet 2 I .m. a 7 7% Q CHARLES fiHmscur-zae.

IN VEN TOR AT RNEY y 1939- c. A. HIRSCHBERG 2,158,120

DETACHABLE DRILL B IT Filed Feb. 19, 1936 3 Sheets-Sheet 3 IN VEN TOR CHQRLES fihmaeusafia.

Patented May 16, 1939 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to drill bits for use in connection with percussive tools and more particularly to detachable drill bits which may be removably attached to a shank drill steel bar, for

replacement when they bepome dulled or worn. The primary object of the present invention is to provide a detachable drill bit as specified which is simple in construction, may be manufactured at a low cost, and one which may be easily, quickly and securely attached to a shank or drill steel without the assistance of any tools.

Another and important object of the present invention is to provide a detachable drill bit which may be forged or formed from lengths of broken or discarded drill steel, and one which lends itself to ready manufacture at the place where it is to be used, or in centralized shops on large projects, much in the same arrangement that drill steels are now sharpened, thereby permitting the user to make the bits as he needs them and eliminating the necessity of tying up large sums of money in a stock of drill bits so as to insure the availability of bits as they are needed.

A further object of the present invention is to provide a detachable drill bit embodying simple, easily connected means for connecting the bit to the shank or drill bar, which means provides a firm multiple point solid connection that is not affected by the blows of the hammer drill and consequently permits easy disconnection of the bit and shank when desired.

With these and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing a detachable drill bit of the preferred form embodying the invention, and the features forming the invention will be specifically pointed out in the claims.

In the drawings:

Fig, 1 is a view partly in section and partly in elevation of the improved detachable drill bit showing it connected to a shank or drill bar taken on the line l| of Fig. 2.

Fig. 2 is a top plan of the detachable bit taken on the line 2-2 of Fig. 1.

Fig. 3 is an end view of the shank by means of which the bit is connected to the bar or drill steel.

Fig. 4 is a diagrammatic plan or diagrammatic development of the drill bit showing the helical groove and slots to permit the insertion of the shank into the socket.

Fig. 5 is' a section taken on the line 5-5 of Fig. 4.

Fig. 6 is a diagrammatic plan or development of the inserting end or shank of the drill steel or drill bar.

Fig. 7 is a section taken on the line 1-1 of Fig. 6.

Fig. 8 is a view partly in section and partly in.

side elevation of a modified form of the detachable drill bit structure illustrating the type wherein the end of the drill bar fits flush against the inner end of the socket in the detachable bit.

Fig. 9 is a fragmentary side elevation of a slight modification in the form of the drill bar or steel and showing splines instead of lugs thereon for connecting the shank to the detachable drill bit.

Fig, 10 is a view partly in section and partly in side elevation of a modified form of the detachable drill bit showing a construction wherein the socket is formed on the drill bar and the shank on the drill bit,

Fig. 11 is an end view of the drill bar looking into the socket.

Fig. 12 is an end view of the bit looking at the end of the shank.

Fig. 13 is a view partly in side elevation and partly in section of a modified form of the type of drill bit illustrated in Figs. 10 to 12 inclusive.

Fig. 14 is a View partly in side elevation and partly in section of a still further modified form of the detachable drill bit structure.

Fig. 15 is an end view of the socket end of the drill bit shown in Fig. 14,

Fig. 16 is a development plan of the socket of the form of drill bit shown in Figs. 14 and 15.

Fig. 1'7 is a section taken on the line ll-l'l of Fig. 16.

Fig. 18 is a view partly in section and partly in elevation of a further modification of the type of drill bit shown inFigs, 14 and 15.

Fig. 19 is a section through a still further modified form of the drill bit taken on the line l9l9 of Fig. 20.

Fig. 20 is a top plan of the modified form of bit shown in Fig. 19.

Fig. 21 is a side elevation of the shank for fitting in the modified form of drill bit shown in Fig. 19.

Fig. 22 is an end view of the shank shown in Fi 21.

Fig. 23 is a cross section taken on the line 23- 23 of Fig. 19.

Fig. 24 is an assembled view partly in side elevation and partly in section of a modified form of the structure shown in Figs. 19 to 23 inclusive.

Referring more particularly to the drawings and considering first the preferred form of the" invention illustrated in Figs. 1 to '7 inclusive, the detachable drill bit comprises the drill bar or drill steel l which has a shank 2 formed thereon for insertion into the socket 3 formed in the detachable drill bit 4 and extending inwardly thereinto from the end of the bit on which the cutting edges 5 are formed. The detachable drill bit 4 has a helical shoulder 6 formed therein a predetermined distance inwardly of the open end of the socket 3 and the face of this shoulder 6 is inclined as shown at 1. However, it may be substantially horizontal or at any other angle than that shown in the drawings, if desired, without departing from the spirit of the present invention.

The helical shoulder 6 which is annular, is interrupted at circumferentially spaced points by slots or grooves 8, 9 and H), which extend inwardly longitudinally of the drill bit from the mouth of the socket 3 to the inner end of the shoulder 6, forming in effect, as clearly illustrated in the development plan shown in Fig, 4, a plurality of projections extending into the socket 3 at circumferentially spaced points on the lower ends of which projections the angular shoulders 6 are formed.

The shank 2 has lugs l2, l3, and I4 formed thereon at circumferentially spaced points which are just slightly narrower than the widths of the slots or grooves 8, 9 and It, so that they may be moved downwardly through the grooves into the socket 3 to a point below or inwardly of the helical shoulder 6. After they are so inserted the drill 'bit 4 is given a partial turn to move the lugs beneath the respective sections of the shoulder.

In the form illustrated in Fig. 1, the drill bar or steel I has an annular collar l5 formed thereon which fits tightly against the upper end of the bit 4 and transmits the blow of the hammer engine (not shown) to the bit. By provision of the helical substantially annular shoulder 6 and by the inclining of the ends of the lugs I2, l3, and I4 to correspond to the helix angle of the shoulder 6, the collar IE will be tightly clamped against the end of the bit 4 when the bit 4 is rotated after the shank 2 has been inserted the proper distance into the socket 3. A further advantage of the helical shoulder 6 is that in many drilling projects the drill bit is rotated during the drilling action and therefore by forming the annular shoulder 6 helical and angling it in the proper direction, namely the direction reversely of the direction of rotation of the drill bit, the rotarymovement of the drill bit during operation will tend to tighten the bit 4 on the shank 2.

In Fig". 4 and 6, the helix angle of the shoulder 6 and the angle of the ends of the lugs l2, l3 and I4, is illustrated as an angle of three degrees which has been found to be approximately the most practical angle, although it is to be understood that the present invention is not to be limited to an angle of three degrees but may be varied widely within practical practice.

- By particular reference to Figs. 2, 3, 4 and 6, it will be noted that the slot or groove 9 and the lug I3, are wider than the slots or grooves 8 and I0, and the lugs l2 and I4. This'is provided so that it Will be impossible for a user'to improperly insert the shank 2 into the socket 3 and will insure the engagement of the respective lugs with the respective parts of the shoulder 6 to provide the tight, firm and solid connection of the bit 4 to the bar or steel Referring particularly to Fig. 4, the width A of the groove 9 will be shown to be reater than the widths B of the grooves 8 and I0, and likewise the width C of the lug l3 in Fig. 6 is shown as being greater than the Widths D of the lugs l2 and M.

In Fig. 8 a modified construction of the detachable drill bit is shown wherein the drill bar or steel I is straight and is not provided with a collar corresponding to the collar I 5. The lugs l2, l3, and M are formed on the end of the bar or steel I, and they engage against an annular helical shoulder 6 which is identical in construction to the shoulder 6. The only difference between this modified form shown in Fig. 8 and the preferred form shown in Figs. 1 to 7 inclusive, is that when the bit 4" is rotated after the shank of the bar or steel I has been inserted into the socket 3', the end of the shank 2 will be forced into engagement with the inner end I 6 of the socket 2' for the purpose of transmitting the blows of the hammer engine (not shown) to the bit 4'.

Fig. 9 shows a further modification of the bar or drill steel and in this modification the shank 2" of the bar or steel I" has splines l1 formed thereon in place of the lugs l2, l3 and I4. The upper ends I 8 of the splines ll are angled to correspond to the helix angle of the shoulders 6 or 6, and this type of shank may be used in connection with the drill bit' 4 in lieu of the constructions of shanks shown in Figs. 1 and 8, if it is so desired.

The construction of detachable drill bit shown in Figs. 1 to 8 inclusive, is formed by forging operations and can be forged from suitable lengths or slugs of broken drill steel or discarded drill steel so as to permit an operator to salvage this expensive material which is normally waste and loss to him. I

In manufacturing the bits 4 or 4', a proper length of drill steel is heated and the cutting end is forged thereon and while it is still heated the socket is punched in the end of the slug of drill steel, the slug being held in suitable dies so as to control its form after which a suitable die is inserted into the socket and portions of the bit about-the socket are forced inwardly as shown at l9 in Figs. 1 and 2 of the drawings. These forcedin portions l9 form the shoulders 6 while the portions 20 which are between the forced-in portions I9, are left in their original normal positions which provides the slots or grooves 8, 9, and

l0 by means of which the lugs l2, l3, and M are inserted into the socket for engagement against the shoulders 6. After the socket, shoulder 6, and various grooves have been forged into or upon the bit 4, the bit is then cooled and treated in the proper manner to harden it for use.

It will be apparent that these detachable bits which particularly lend themselves to manufacture by forging operations, can be manufactured at a much lower cost than can bits which are machined or require machining operations in their manufacture. Also they can be manufactured at the place where they-are to be used or in close proximity thereto, such as in the shops which are now used for sharpening drill steels.

The shank or inserting end of the bar I may also be forged in that all that is necessary is first to heat and upset one end of the bar or drill steel I or I and then reshape it in dies by forging operation to provide either the lugs l2, l3 and I4, and'splines l1, and also to either form the collar IE or leave the shank free from the collar as per the construction shown in Fig. 8 of the drawings.

In Figs. 10 to 13 inclusive, a modification of the improved detachable drill bit is shown and 3| has an annular helical shoulder 33 formed therein which is substantially the same in construction as the annular helical shoulder 6 formed in the socket 3, and this annular helical shoulder 32 is interrupted at circumferentially spaced points by slots or grooves 34, 35, and 36 which extend inwardly from the open end or mouth of the socket into and through the shoulder 33 to permit insertion of the lugs 31, 38, and 39 into the socket 3| for engagement with the shoulder to detachably connect the drill bit 48 to the drill steel or bar 38. After the shank 4|, which is formed on the bit 48, is inserted into the socket 3| a sufi'icient distance, the drill bit is rotated slightly to move the lugs 31, 38, and 39 out of registration with the grooves or slots 34, 35, and 36 and beneath the shoulder'33 for the purpose of securely connecting the drill bit 48 to the bar or steel 38. The drill bit 48 has any approved type of cutting edges as shown at 42 formed thereon.

As shown clearly in Figs. 11 and 12, the slot or groove 35 and the lug 38 are wider than the slots 34and 36, and the lugs 31 and 39 so as to insure the proper positioning of the bit 48 with respect to the steel or bar 38 when these two are being connected.

In the construction shown in Fig. 10, the blowtransmitting surface between the bar 38 and the bit 48 is provided by'the outer end of the enlarged end portion 32 of the bar 38 having contact with and bearing against the shoulder 43 formed on the bit 48 at the inner terminus of the shank 4|, and the modified construction shown in Fig. 13 is in all ways similar to the construction shown in Figs. 10 to 12 inclusive, excepting only as to the point of impact transmitting contact between the bit 48' and the bar or steel 38.

In the modified construction shown in Fig. 13, the shank 4| is of sufficient length that its outer end 44 contacts with the inner end 45 of the socket 3|, while the outer end of the'enlarged portion 32 of the bar 38' is free from contact or engagement with the shoulder 43 formed on the bit 48'. In all other respects the construction shown in Fig. 13 is similar to the construction shown in Fig. 10.

Figs. 14 to 18 inclusive show another modification of the construction of the detachable drill bit, and this construction unlike the construction shown in Figs. 1 to 8 inclusive is more particularly adapted to be manufactured by the machining operation instead of by forging although it may be manufactured by forging if so desired. In general principles this modification is similar to the construction shown in Figs. 1 to 8, differing therefrom in particular details which will be hereafter pointed out in the specific description of this form.

In Figs. 14 to 1'7 inclusive, the drill steel or bar 58 has a collar 5| thereon the outer or underside 52 of which engages against the upper or outer end 53 of the detachable bit 54 to provide the blow or impact contact between the bar 58 and the bit 54.

The bit 54 is provided with a socket 55 which opens out through its upper end and it has cutting edges 56 of any approved type formed on its end opposite to the contact end 53.

The socket 55 has an annular helical groove 51 formed in its side wall intermediate its ends. A plurality of grooves or slots 58, 59, and 68 extend inwardly from the open end of the socket and open out into the annular helical groove 51,

as clearly shown in diagrammatic development in Fig. 16 and in Fig. 14. The upper and lower edges 59 and 68 of the groove 51 aretshown inclined but they may be made at the incline or bevel shown or in any other desired or beveled manner without departing from the spirit of the present invention. The slots or grooves 58, 59, and 68 permit the insertion of the lugs 6|, 62, and 63 into the annular helical groove 51. The various lugs 6|, 62, and 63 have their ends shaped to conform to the shape of the edges 59 and 68 of the groove 51 and they fit snugly within this groove for firmly, solidly, and securely connecting the drill bit 54 to the drill steel or bar 58. The lugs 6|, 62,.and 63 are formed at circumferentially spaced points on the outer surface of the shank 64 which shank is formed on the end of the drill steel or bar 58 and is inserted into the socket 55. The shank 64, and the lugs 6|, 62, and 63 formed thereon, are substantially the same in construction and arrangement as the shank 2 and the lugs l2, l3,

and I4 which are formed thereon. In fact, the drill bars or steels 58 and I may be interchanged for use with either the drill bit 4 or the drill bit 54, the difference in the structure between the type of detachable bit assembly shown in Fig. 1 and that shown in Fig. 14 being in the construction of the detachable bits themselves.

If it is so desired, any one of the slots 58, 59, or 68 and the corresponding lugs 6|, 62, or 63 may be made larger than the others, for the purpose of insuring proper positioning of the bit 54 relative to the bar 58 when the two are being connected. In Fig. 15 the slot 59 is shown larger or wider than the slots 58 and 68.

The construction shown in Fig. 18 is just the same as the construction shown in Fig. 14, differing therefrom only in the construction of the drill steel or bar. In Fig. 18 the drill steel or bar 58' does not have an annular collar thereon corresponding to the collar 5| but it is straight and substantially of uniform diameter throughout its length having lugs 6|, 62, and 63' formed thereon which correspond to the lugs 6|, 62, and 63, and co-operate with the annular helical groove 58' formed in the socket 55' in the detachable bit 54'. In this Fig. 18 the impact transmitting contacting surface engagement between the bar.or steel 58 and bit 54' is between the end 66 of the bar or steel 58 and the inner end 61 of the socket 55.

While in the foregoing description and in the drawings up to and including Fig. 18, three lugs have been shown which co-operate either with the annular helical shoulders or the annular helical groove for connecting the bit and bar or steel, it is to be understood that any practical number of lugs and corresponding slots or grooves may be provided without departing from th spirit of the present invention.

Figs. 19 to 24 inclusive show another or fur ther modification in the construction of the detachable drill bit which, while in certain features is quite similar to and embodies the same generic principles as the bit and shank structures shown in Figs. 1 to 18, inclusive, departs therefrom in respect to the manner of connection of the bit and shank.

This construction is such that it also, like the structure shown in Figs. 1 to 8, inclusive, particularly lends itself to manufacture wholly by forging operations.

In Fig. 19 a detachable bit is shown which may end thereof, and also it is provided with an axial socket 12 extending inwardly from the end of the bit opposite to the end upon which the.

cutting edges H is formed. The socket 12 has a plurality'of depressions or recesses 13 formed therein at spaced points about its circumference and these depressions are arranged helically, that is, they are disposed at angles to a horizontal plane bi-secting the socket at right angles to the axis thereof, similar or like the helical angle at which the shoulders 6 or groove 51 are disposed.

The depressions or recesses 13 are formed by forging and their walls are curved outwardly from the curvature of the wall of the socket 12 almost tangentially thereto from their entrance ends to their inner or stop ends 14, gradually increasing in depth from their entrance ends towards their inner ends 14. Slots or grooves 15 are formed in the drill bit 10 at circumferentially spaced points about the socket l2 and they are shaped in cross-sectional area like the crosssectional shape of the depressions or recesses 13. They are not however as wide as the depressions or recesses are long so that the depressions or recesses project to one side of the grooves 15, as clearly shown in Figs. 19 and 23, to provide shoulders 16 against which the lugs 11 formed on the shank l8 engage. The shank I8 is formed on one end of a drill steel or bar 19. The lugs 11 are shaped in plan or cross-sectional area to correspond to the cross-sectional shape of the slots or grooves and the depressions or recesses 13 and they are of substantially the same size as the grooves 15, so that these lugs 11 may pass through the grooves 15 during the insertion of the shank 18 into the socket 12. When the lugs I! reach the depressions or recesses 13 the bit 18 or the bar or steel 19 are rotated slightly so as to bring the larger ends of the lugs 11 beneath and in engagement with the shoulders 16 to securely connect the bit 10 and the steel or bar 19.

The lugs 11 are eccentric of the outer circular surface of the shank 18 as are the depressions or recesses 13 with respect to the curved wall of the socket 12.

In the construction shown in Figs. 19 to 23 inclusive, the drill steel or bar 19 has an annular collar 88 formed thereon, the under-surface 8| of which contacts with the upper end 82 of the detachable bit 10 toprovide the impact transmitting contact between the bar or steel 19 and the bit 10.

In Fig. 24, the detachable bit w is identical in construction with the bit 10 including the depressions or recesses 13 and the grooves or slots 15 as well as the other features of the bit 10. This construction differing from the construction in Figs. 19 to 22 in the arrangement of the impact transmitting contacting surfaces. The steel or bar 19 is inserted all of the way into the socket 12 so that its inner end 85 contacts with the inner end 86 of the socket to provide the impact transmitting contact of the bar and bit. In all other respects with the exception of the annular collar 88, the steel or bar '39 is like the steel or bar 19, having lugs 11' thereon which are like the lugs 11.

While the construction shown in Figs. 10 to 13, inclusive, namely the structure wherein the socket is formed on the drill steel or bar with the shank formed on the drill bit, shows only the method of construction comprising the annular helical shoulders, it is to be understood that the annular helical groove feature such as disclosed in Figs. 14 to 18 inclusive or the eccentric depression and lug structure for connecting the bit and shank as shown in views Hi to 24 inclusive, may be applied to the structures wherein the shank is formed upon the bit and the socket upon the bar without departing from the spirit of the present invention, and also it is to be understood that any of the various arrangements of connecting the bit and shank may be embodied in any of the various constructions of bit and shank, without departing from the spirit of the present invention.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown but that they may be widely modified within the invention defined by the claims.

What is claimed is:

1. In a detachable drill bit, in combination, a drill bit for attachment to a shank having cutting edges on one end and provided with an axial socket extending inwardly from the other end, portions of said drill bit about said socket being pressed inwardly for a predetermined distance from the mouth of the socket to form an annular shoulder within the socket, certain spaced portions of the bit being left in their normal positions to form grooves extending longitudinally into the socket and interrupting said shoulder, a shank, a plurality of circumferentially spaced projections on said shank for engagement beneath said shoulder, one of said grooves being wider than the remaining grooves, one of said projections being wider than the other spaced projections, and a collar on said shank for engagement with the outer end of said bit to provide impact transmitting contact between the shank and bit.

2. In a detachable drill bit, the combination of a socket member having a socket therein, a helical shoulder in said socket, a. shank for insertion into the socket, circum-ferentially spaced projections on said shank being located longitudinally of the shank in such positions as each to have contact only with a respective portion of said helical shoulder, said socket member having longitudinally extending grooves therein opening out inwardly of said shoulder to permit insertion of said projections into the socket for engagement against the shoulder, one of said grooves being larger than the others and. one of said projections being wider than the other projections so as to insure the proper positioning of the socket. and shank when connected, a collar on said shank for engagement with the outer 

